VERY heavy clutch pedal

Greetings -
Driving my father's Cherokee this weekend I almost blew my ACL trying to make my way along in stop-and-go driving. It is easily twice as hard to press as the clutch pedal in my Cherokee.
The clutch doesn't slip or anything like that.
He doesn't even notice it as he said that it has been that way ever since he had his clutch and MC replaced 3 years ago. Occasionally it grinds when putting it into gear or will sort of "lock up".

Any one have any advice?

Give some stats on his Cherokee. Miles, year, tranny, etc.

It's hard to answer if we don't know the situation.

Thanks, here are some more details:

75k miles
1998
AX-15

My 94's pedal effort was greatly reduced when the fork and surfaces inside the bellhousing were cleaned and greased during a clutch install. My 96 requires double the effort. My left calf has more muscle than my right from 12+years pushing that pedal in.